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CARLSO!':. HANMOND & PADDOCK A IT ACHMEN: Agenda Item 7.a.11. January 19, 1994 Daries C. lile, P.E. Colorado Uater,Conservation Board January S. 1994 Page 2 In order to have the storage restriction lifted, the Company needs to design new remedial measures that will effectively reduce or eliminate the embankment seepage. To this end, the company contacted the consulting engineering firm of HARZA Northwest, Inc. which successfully designed and implemented repairs for Rio Grande Reservoir in 1988 and in 1993. HARZA was provided available information on Continental Dam and was asked to make. recommen- dations on the cause of and potential solutions to the on-going seepage problem at Continental Dam. By letter dated October 28, 1993, HARZA provided the Company with its analysis of the conditions at Continental Dam and concluded that there was insufficient information available to determine the precise seepage mechanism. HARZA therefore recommended that additional information be obtained on the dam embankment and abutment before any additional repairs are evaluated. A copy of HARZA's letter is attached for your reference. To collect the necessary information, HARZA recommends the drilling of five cored and sampled bore holes, four in the dam's embankment and one in the left abutment. The four borings into the embankment of the dam would be completed as piezometers for long- term monitoring. The fifth boring would be made into the left abutment of the dam for purposes of determining the conditions in the abutment and the mechanisms for flow of water through the abutment and into the dam embankment. The information obtained from. these borings would, in the judgment of HARZA, be sufficient to allow it to design repairs that would minimize seepage and achieve an effective factor of safety for the dam. The cost of this initial data collection is estimated to be $48,500. The Company requests the Water Conservation Board to loan it one-half of the cost and to make a grant for one-half of the cost for this additional feasibillty study. The Company proposes to repay its share of the feasibility study in cash. In order to make cash available for this purpose, the company requests a one-year deferral of its scheduled 1994 payment of $33,175.48 to the Board under Contract No. C-l53386, or one-half of the study cost, whichever is less. ~ The Company believes that a grant of one-half of the study cost is justified because of the importance to the state of Colorado in preserving pre-compact storage in the San Luis Valley. Continental Reservoir is one of only three reservoirs of any size on the Rio Grande that pre-dates the Rio Grande Compact. Under the Rio Grande Compact, reservoirs constructed prior to 1929 operate free of any restraint on storage so long as Colorado is in